A photoelectric conversion device utilizing an organic metal perovskite-type crystal material (perovskite photoelectric conversion device) can provide a high conversion efficiency, and a large number of reports have recently been published on improvement on conversion efficiency (e.g., Non-Patent Document 1 and Patent Document 1). Example of the organic metal includes a compound represented by a general formula RNH3MX3 or HC(NH2)2MX3 (where R is an alkyl group, M is a divalent metal ion, and X is a halogen). Spectral sensitivity characteristics of the compound are known to vary depending on the halogen and/or the ratio of the halogen (e.g., Non-Patent Document 2).
A perovskite-type crystal material, such as CH3NH3PbX3 (X: halogen), can be formed by a vapor deposition, spin coating and the like. Especially a thin-film can be formed in low cost with using a solution coating method such as spin coating. Thus, attention has been directed to a perovskite photoelectric conversion device as a low-cost and high-efficiency next generation photoelectric conversion device.
For example, a perovskite-type crystal material using iodine as a halogen has a spectral sensitivity characteristic at a wavelength shorter than a wavelength of 800 nm, and absorbs little infrared light having a wavelength longer than 800 nm. Thus, for improvement of the conversion efficiency of a photoelectric conversion device including a perovskite-type crystal material, it is important to effectively utilize long-wavelength light which is absorbed only in a small amount by the perovskite-type crystal material.
For example, Non-Patent Document 3 discloses a double-junction solar cell in which on a crystalline silicon photoelectric conversion unit including a p-type emitter layer on a light-receiving side surface of an n-type single-crystalline silicon substrate, a perovskite photoelectric conversion unit is provided with an n-type tunnel junction layer and a TiO2 layer interposed therebetween, and a crystalline silicon photoelectric conversion unit and a perovskite photoelectric conversion unit are connected in series.